The present disclosure relates generally to fluid dispensing systems. More specifically, this disclosure relates to displacement pumps for fluid dispensing systems.
Fluid dispensing systems, such as fluid dispensing systems for paint and other solutions, typically utilize axial displacement pumps to pull a fluid from a source and to drive the fluid downstream. The axial displacement pump includes a piston that is driven in a reciprocatory manner along its longitudinal axis to pump the fluid. As the piston reciprocates, fluid is drawn into the piston, flows through a central bore aligned with the longitudinal axis, and flows out of the piston through a second bore, and optionally a third bore, oriented orthogonal to the longitudinal axis. The second bore and optional third bore turn the fluid at a right angle to the longitudinal axis, such that the fluid exits the piston orthogonal to the longitudinal axis. Flowing the fluid through the piston and turning the fluid out of the cross-bore increases hydraulic resistance, induces turbulence in the fluid, and reduces the flow rate of the fluid; in addition, the flow area through the piston is limited by the diameter of the piston and the cross-bore, and the limited flow area also causes increased hydraulic resistance and induces turbulent flow.